Semi-micro analytical balance is a highly-accurate balance that is used to accurately determine the exact weight of fine objects. With an accuracy of 0.01mg, a semi-micro analytical balance has one more decimal place than a macro analytical balance, so it is capable of producing more accurate results.

Structure

A semi-micro balance is made up of the same general components as a macro analytical balance. It usually consists of draft windshields, a weighing pan, a draft shield ring, a display panel, a keyboard, four leveling feet, a level bubble, a rs-232 interface, a power inlet, a power cable, a calibration weight, a battery and the balance’s main body. The main difference between a macro and a semi-micro analytical balance is the draft shield ring around the weighing pan, which is designed to further reduce the influence of air current on measurements.

Calibration

The semi-micro balance can be calibrated in two ways. The first is external calibration. The instruction manual should provide steps for such procedure which normally uses a calibration weight that comes with the balance.

The second method is internal calibration. The balance can automatically perform the calibration processwith the help of its built-in calibration weight. Semi-micro balances usually come with this internal calibration function, simply press the internal-calibration button when calibration is required, and the balance will do the calibration by itself.Some of the macro analytical balance also comes with internal calibration function.

Weighing

Prior to each weighing, zero the balance in no-load state. Then open one of the bilateral glass doors, place the sample on the weighing pan and close the glass door. Once the stability indicator on the panel appears, read the weight indicated on the display.

For samples that need to be placed in a container, first open one of the bilateral glass doors and place the container onto the weighing pan, then close the door and tare the balance. The following steps are basically the same as weighing without a container: open one glass door, place the sample into the container, and close the door, and then read the value from the screen once the stability indicator appears.

Maintenance

In order to keep a semi-micro balance functioning properly, it's important to keep it clean and well-maintained.

To clean the balance, first make sure the power is switched off and the power cord is unplugged. Use a lint-free cloth and a mild detergent such as a small amount of dish soap. Don't use any harsh or abrasive cleaning agents or solvents.

In order to access the entire balance for cleaning, the sliding glass doors need to be removed. First, remove the pan and anti-draft ring from the weighing chamber, then unscrew and remove the inside knob on the glass door, and finally slide the glass door out backwards.

Applications

Semi-micro balances can be used in quantitative chemical analysis, in which even very small changes in mass will have a great impact on the results. Similarly, semi-micro balances are also used in pharmaceutical research in institutes of pharmacology and pharmaceuticals companies.

Price

The price range of semi-micro analytical balances ranges from $1,500 to $20,000. Due to technical thresholds, some brands of semi-micro balances have higher premiums. For example, XPE205 Semi-micro balance will cost about 16000 dollars.In contrast, U.S. Solid USS-DBS84 Semi-micro analytical balance currently has a price of only $1599.

References
[1] Hugo Donaldson. (2019 July 17): THE IMPORTANCE OF SEMI MICRO BALANCE IN LABORATORIES. https://www.statsglobe.com/the-importance-of-semi-micro-balance-in-laboratories/
[2] Sarah Moore. (2020 June 17): What is a Microbalance?.
https://www.news-medical.net/life-sciences/What-is-a-Microbalance.aspx
[3] mt.com. : MS Semi-Micro Balances. https://www.mt.com/us/en/home/products/Laboratory_Weighing_Solutions/Analytical/Advanced/semi-micro-balance.html#overviewpl
[4] coleparmer.com. : Semi and Micro Analytical Balances. https://www.coleparmer.com/